This invention relates to grippers and more specifically to parallel type grippers for use with a machine tool or robotic machines.
Various constructions of mechanical grippers for use with machine tools and/or robotic tools for holding and/or locating a work piece are known. Such known grippers have been disclosed in various U.S. Patents, e.g. U.S. Pat. Nos. 4,593,948; 4,741,568; 4,874,194; 5,125,708; 5,163,720; 5,529,359; 5,572,915; 5,976,581 and 6,003,431. While these known grippers are useful for their intended purposes, there still persists certain problems and/or deficiencies, e.g. increasing and/or enhancing the range of movement between the open and closed position of the gripper fingers for a given size gripper housing or envelope. In other words, that the range between the open and closed positions of the gripper fingers is greater than that of a known gripper of equal size.
A feature of this improved gripper resides in providing a gripper of a given envelope size, i.e. housing, having a greater range of movement between an opened and closed position of the gripper fingers carried thereon. In other words, the range between the open and closed position is greater than that of a known unit of equal size.
Another feature resides in the provision that the gripper disclosed herein is relatively simple and economical to fabricate.
The foregoing features, objects and other advantages of this invention are attained by a gripper that includes a housing having a cylinder bore extending therethrough which is sealed on the opposite ends thereof. A piston is slidably disposed within said cylinder bore for reciprocating therein. In one form of the invention, the piston is activated to reciprocate in either direction by fluid pressure, e.g. compressed air. In another form of the invention, the piston is fluid activated in one direction and spring biased to shift the piston in the opposite direction.
In either event, the housing is provided with a cruciform slot extending parallel to the axis of the cylindrical bore. A pair of cruciform finger carriers are reciprocally mounted within the cruciform slot to slide between an open and closed position. A suitable gripper finger is carried on each of the finger carriers which are arranged to grip a work piece therebetween.
In accordance with this invention, one of the finger carriers is provided with a rack disposed in meshing relationship to an idler gear rotatably journaled within the housing between the piston and the rack of the finger carrier. The piston is also provided with a rack disposed in meshing relationship with the idler gear.
The other finger carrier is pinned to the piston at a point longitudinally spaced from the axis of rotation of the idler gear. The arrangement is such that the finger carriers and the fingers carried thereby are shifted between open and closed position in synchronization with the displacement or reciprocation of the piston whereby the range of movement between the open and closed position of the gripper fingers is enhanced from the known grippers of comparable size.